The Akro-Mils 30292-Yellow Super-Size AkroBin® Stackable Shelf Bin is molded of high-impact polypropylene block co-polymer, which is unaffected by weak acids and alkalis. This sturdy 1-piece construction is also water-, rust-, and corrosion-proof. This heavy-duty bin can stack securely on one another and sit on shelving, carts, or dollies (Please note it is not recommended to use on hanging systems).